Unfortunately, in CRM 7.0 you will not be able to print mail forms as you did in CRM 5.0. You can use CRM and the file export function to export the data then use a third party tool to format and print the letters. Another option would be to create an Open chennel BADI that uses the code from the old CRM version.

Thx Andrei, I know these notes and I have them in my system but I do not fully understand how it works. Can you please post example user steps for such letter campaign? (how the print is done - from activity or any bulk job)

I had to create form for letter but could do it only in tcode CRMD_EMAIL - I did not find any place in web ui to create it. I had also to create print profile for campaign. And later I set it all on campaign, and it works.